title: CDK5-dependent phosphorylation of the Rho family GTPase TC10(alpha) regulates insulin-stimulated GLUT4 translocation.
abstract: Insulin stimulation results in the activation of cyclin-dependent kinase-5 (CDK5) in lipid raft domains via a Fyn-dependent phosphorylation on tyrosine residue 15. In turn, activated CDK5 phosphorylates the Rho family GTP-binding protein TC10alpha on threonine 197 that is sensitive to the CDK5 inhibitor olomoucine and blocked by small interfering RNA-mediated knockdown of CDK5. The phosphorylation deficient mutant T197A-TC10alpha was not phosphorylated and excluded from the lipid raft domain, whereas the phosphorylation mimetic mutant (T197D-TC10alpha) was lipid raft localized. Insulin resulted in the GTP loading of T197D-TC10alpha but not T197A-TC10alpha and in parallel, T197D-TC10alpha but not T197A-TC10alpha depolymerized cortical actin and inhibited insulin-stimulated GLUT4 translocation. These data demonstrate that CDK5-dependent phosphorylation maintains TC10alpha in lipid raft compartments thereby disrupting cortical actin, whereas subsequent dephosphorylation of TC10alpha through inactivation of CDK5 allows for the re-assembly of F-actin. Because cortical actin reorganization is required for insulin-stimulated GLUT4 translocation, these data are consistent with a CDK5-dependent TC10alpha cycling between lipid raft and non-lipid raft compartments.
authors.affiliation: Department of Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma 371-0034, Japan. okadash@showa.gunma-u.ac.jp
authors.forename: Shuichi
authors.initials: S
authors.lastname: Okada
authors.forename: Eijiro
authors.initials: E
authors.lastname: Yamada
authors.forename: Tsugumichi
authors.initials: T
authors.lastname: Saito
authors.forename: Kihachi
authors.initials: K
authors.lastname: Ohshima
authors.forename: Koshi
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Masanobu
authors.initials: M
authors.lastname: Yamada
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Uehara
authors.forename: Takafumi
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shimizu
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Tatei
authors.forename: Takashi
authors.initials: T
authors.lastname: Izumi
authors.forename: Keishi
authors.initials: K
authors.lastname: Yamauchi
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Hisanaga
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Pessin
authors.forename: Masatomo
authors.initials: M
authors.lastname: Mori
mesh_terms: D041721:3T3-L1 Cells; D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D051360:Cyclin-Dependent Kinase 5 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051275:Glucose Transporter Type 4 / Q000235:genetics / Q000378:metabolism*; D007328:Insulin / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D007701:Kinetin / Q000494:pharmacology; D021962:Membrane Microdomains / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D004791:Enzyme Inhibitors; D051275:Glucose Transporter Type 4; D007328:Insulin; D034741:RNA, Small Interfering; C495693:Slc2a4 protein, mouse; C090046:olomoucine; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D051360:Cyclin-Dependent Kinase 5; C495906:Cdk5 protein, mouse; C503260:Rhoq protein, mouse; D020741:rho GTP-Binding Proteins; D007701:Kinetin